Discontinuous transmission (DTX) detection using decoder metric

Abstract

A method detects an absence of a transmitted frame in a wireless communications system that operates with a discontinuous transmission (DTX) protocol between a transmitter and a receiver. The method includes decoding a received signal over a frame period to determine a cumulative metric; normalizing the cumulative metric and comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame. The determined cumulative metric may be a maximum cumulative metric or a zero state cumulative metric. The wireless communications system may be a CDMA system, the receiver may be contained within a mobile station, and the determination of whether the frame was a transmitted frame or a non-transmitted frame can be employed, as one non-limiting example, during execution of a power control algorithm.

1. A method for detecting an absence of a transmitted frame in a wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 decoding a received signal over a frame period to determine a cumulative metric;  
 normalizing the cumulative metric; and  
 comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame.  
 
   
   
     2. A method as in  claim 1 , where the determined cumulative metric comprises a maximum cumulative metric. 
   
   
     3. A method as in  claim 1 , where the determined cumulative metric comprises a zero state cumulative metric. 
   
   
     4. A method as in  claim 1 , where the wireless communications system comprises a code division, multiple access system. 
   
   
     5. A method as in  claim 4 , where the received signal is received from a Forward Dedicated Control Channel (F-DCCH). 
   
   
     6. A method as in  claim 4 , where the received signal is received from a Forward Supplemental Channel 1 (F-SCH 1). 
   
   
     7. A method as in  claim 4 , where the received signal is received from a Forward Supplemental Channel 2 (F-SCH2). 
   
   
     8. A method as in  claim 4 , where the receiver comprises a part of a mobile station, and where the determination of whether the frame was a transmitted frame or a non-transmitted frame is employed during execution of a power control algorithm. 
   
   
     9. A method for detecting an absence of a transmitted frame in a wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 decoding a received signal over a frame period to determine a cumulative metric;  
 normalizing the cumulative metric; and  
 comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame, where  
 normalizing comprises squaring the determined cumulative metric, and dividing the squared determined cumulative metric by an estimated pilot power and noise variance.  
 
   
   
     10. A method for detecting an absence of a transmitted frame in a wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 decoding a received signal over a frame period to determine a cumulative metric;  
 normalizing the cumulative metric; and  
 comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame, where  
 normalizing also comprises dividing by the frame length.  
 
   
   
     11. A wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 a decoder for decoding a received signal over a frame period to obtain a cumulative metric;  
 a normalizer for normalizing the cumulative metric; and  
 a comparator for comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame.  
 
   
   
     12. A wireless communications system as in  claim 11 , where the decoder outputs a maximum cumulative metric. 
   
   
     13. A wireless communications system as in  claim 11 , where the decoder outputs a zero state cumulative metric. 
   
   
     14. A wireless communications system as in  claim 11 , where the wireless communications system comprises a code division, multiple access system. 
   
   
     15. A wireless communications system as in  claim 14 , where the received signal is received from a Forward Dedicated Control Channel (F-DCCH). 
   
   
     16. A wireless communications system as in  claim 14 , where the received signal is received from a Forward Supplemental Channel 1 (F-SCH1). 
   
   
     17. A wireless communications system as in  claim 14 , where the received signal is received from a Forward Supplemental Channel 2 (F-SCH2). 
   
   
     18. A wireless communications system as in  claim 14 , where the receiver comprises a part of a mobile station, and where the determination of whether the frame was a transmitted frame or non-transmitted frame is employed during execution of a power control algorithm. 
   
   
     19. A wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 a decoder for decoding a received signal over a frame period to obtain a cumulative metric;  
 a normalizer for normalizing the cumulative metric; and  
 a comparator for comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame, where  
 the normalizer comprises means for squaring the determined cumulative metric, and means for dividing the squared determined cumulative metric by an estimated pilot power and noise variance.  
 
   
   
     20. A wireless communications system that operates with a discontinuous transmission protocol between a transmitter and a receiver, comprising:
 a decoder for decoding a received signal over a frame period to obtain a cumulative metric;  
 a normalizer for normalizing the cumulative metric; and  
 a comparator for comparing the normalized cumulative metric to a threshold for determining whether the frame was a transmitted frame or a non-transmitted frame, where  
 the normalizer further comprises means for dividing by the frame length.  
 
   
   
     21. A method for detecting an absence of a transmitted frame in a wireless code division, multiple access communications system that operates with a discontinuous transmission (DTX) protocol between a base station transmitter and a mobile station receiver, comprising:
 decoding a signal received from a convolutional channel over a frame period to determine a cumulative metric;  
 normalizing the cumulative metric, comprising squaring the determined cumulative metric, and dividing the squared determined cumulative metric by an estimated pilot power and noise variance; and  
 comparing the normalized cumulative metric to a threshold for determining whether the frame was a DTX frame or a non-DTX frame.  
 
   
   
     22. A method as in  claim 21 , where the determined cumulative metric comprises one of a maximum cumulative metric and a zero state cumulative metric. 
   
   
     23. A method as in  claim 21 , where the received signal is received from one of a Forward Dedicated Control Channel (F-DCCH), a Forward Supplemental Channel 1 (F-SCH1) and a Forward Supplemental Channel 2 (F-SCH2). 
   
   
     24. A method as in  claim 21 , where the determination of whether the frame was a DTX frame or a non-DTX frame is employed during execution of at least one mobile station power control algorithm. 
   
   
     25. A method as in  claim 21 , where normalizing further comprises dividing the determined cumulative metric by the frame length prior to squaring. 
   
   
     26. A method as in  claim 25 , where dividing the squared determined cumulative metric comprises dividing by a multi-finger form of the estimated pilot power and noise variance. 
   
   
     27. A receiver for use in a wireless code division, multiple access communications system that operates with a discontinuous transmission (DTX) protocol between a transmitter and the receiver, comprising:
 a decoder to decode a signal received from a channel during a frame period to determine a cumulative metric;  
 a normalizer coupled to an output of the decoder to normalize the cumulative metric by operations that comprise squaring the determined cumulative metric, and dividing the squared determined cumulative metric by an estimated pilot power and noise variance; and  
 a comparator coupled to an output of the normalizer to compares the normalized cumulative metric to a threshold so as to determine whether a received frame was a DTX frame or a non-DTX frame.  
 
   
   
     28. A receiver as in  claim 27 , where the determined cumulative metric comprises one of a maximum cumulative metric and a zero state cumulative metric. 
   
   
     29. A receiver as in  claim 27 , where the signal is received from one of a Forward Dedicated Control Channel (F-DCCH), a Forward Supplemental Channel 1 (F-SCH1) and a Forward Supplemental Channel 2 (F-SCH2). 
   
   
     30. A receiver as in  claim 27 , where the determination of whether the frame was a DTX frame or a non-DTX frame is considered during execution of a power control algorithm. 
   
   
     31. A receiver as in  claim 27 , where said normalizer comprises a divider to divide the determined cumulative metric by a length of the frame prior to squaring. 
   
   
     32. A receiver as in  claim 31 , where the divider further divides by a multi-finger form of the estimated pilot power and noise variance.